Drill sharpening machine



Feb. 14, 1939. 3. B. AMBLERv v 2,14227 DRILL SHARPENING MACHINE` FiledJan. /l4, 1955 3 Sheets-Sheet l Feb. 14, 1939. G. B. AMBLER 2,147,227

DRILL SHARPENING MACHINE Filed Jan. 14, 1935 3 Sheets-Sheet 2 l l 'j ,mil: f 68 30A i (i 1 @I 64 mi he 30 /ae [awe/22122031:

Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE Diamond Saw & MachineWorks, Inc., Natick,

Mass., a corporation of Maine Application January 14, 1935, Serial No.1,655

3 Claims.

This invention relates to machines for sharpening twist drills and theobject is to provide a mechanism simple in construction and convenientin use which will perform the desired work with a high degree ofaccuracy. It has hitherto been proposed to provide a drill-sharpeningmachine wherein a holder for the drill is guided in its movementrelatively to a grinding wheel to provide for the proper sharpening andshaping of the lips of the drill. My invention contemplates a machine ofthis general type having features of construction promoting conveniencein use and accuracy in result.

My invention will be well understood by reference to the followingdescription taken in connection with the accompanying drawings, wherein.

Fig. 1 is a plan of the machine; Fig. 2 is an end elevation as seen fromthe right zl" of Fig. 1;

Fig. 3 is a section showing a drill to be sharpened inserted in acarrying sleeve;

Fig. 4 is an end view of the same on an enlarged scale; Fig. 5 is a.longitudinal section showing the sleeve and drill of Fig. 3 inserted ina holder;

Fig. 6` is a longitudinal section showing the holder of Fig. 5 insertedin gaging mechanism for properly positioning the drill therein; and

Fig. '7 is a section showing the holder in position in a movable supportto position it relative to the grinding wheel.

Referring now more particularly to Figs. 1 and 2 of the drawings, themachine there shown comprises a suitable base 8 having ways Illreceiving the base l2 of an electric motor I4, the rotor shaft of whichcarries a grinding wheel I6. An adjusting screw I8 (Fig. l) cooperatingwith a segmental nut 2S on the bottom of the motor casing provides forlongitudinal adjustment of the motor and the wheel. This arrangementprovides for initial positioning and for compensating wear of the wheel.In the ordinary use of the machine the wheel I6 revolves in a fixedplane and may be secured by clamping bolts 2 l, one of which is seen inFig. 2. Herein the radial face of the wheel l5 is utilized to sharpenthe drill but I have shown the wheel as provided with a radiallyextending portion 22 adjacent its rear radial face providing 50 a narrowperipheral edge which may be utilized for thinning out the webs of thedrills when they are shortened by repeated grinding.

The means for holding and guiding the drill while its end is beingsharpened comprise a sup- 55 port 24 carried (see Fig. 2) by a bracketarm 26 adapted to swing about a. post 2B formed on a base 3l) secured tothe main base 8 of the machine and so oriented relative to the verticalline passing through the point of contact of the drill and the wheel inuse as to provide under the control of 5 l the mechanisms hereinafter tobe described a proper angle to the cutting lips of the drill, having inView the material in which it is to be used. Also carried by the postand projecting rearwardly at'one side of the holder is an arm 32, best10 seen in Fig. 1, which is adapted to cooperate with the edge cam 42,hereinafter to be described, a spring 34 normally tending to swing thesupport 24 towards the arm 32. The support 24 is provided with acylindrical opening 36 therethrough, 15 herein dened by a hardened bush(see Fig. 7) forming a bearing in which the drill holder hereinafter tobe described is adapted to slide and turn.

The drill holder, as illustrated in Fig. 5, has a 2U cylindrical bodyportion 38 adapted to fit the bearing bush 36 and is provided with alongitudinal opening therethrough presenting at least in part anaccurate, coaxial, cylindrical bearing 40. This body 38 is adapted to beinserted into the 25 bearing opening 36 of the support 24 from the rear,that is, from the side remote from the wheel I 6, as illustrated in Fig.'7. At the outer end of the body there is secured a double-rise edge'cam 42, best seen in Fig. 1, which cooperates with the 30 arm 32, andon the forward face of this cam are provided at diametrically opposedpoints pins 44 which may cooperate with a face cam 46, best seen in Fig.7, secured to the rear face of the support 24. When the holder isinserted in the sup- 35 port from the rear, as shown in Fig. '7, andpressed forwardly towards the wheel and at the same time rotated, thecooperation of a pin 44 with cam surface 46 will advance the drilltowards the wheel while at the same time the 'cooperation of a rise 4Uof the edge cam 42, which is held by the spring 34 towards the ilXed arm32, causes the angular relation of the drill to the face of the wheel t0be suitably controlled so that the lip of the drill is properly backed01T. One lip of the drill is ground 45 during a half rotation of theholder and the drill is then withdrawn by the action of cam 46 and theother lip is similarly ground by cooperation of the other pin 44 withthe cam 46 and of the other rise of cam 42 with arm 32.

A further description of elements of the machine by which an accuratecentering of the drill in the holder and an accurate angular positioningof the same relative to the cams which control its motion are providedmay perhaps be most readily 55 understood if I describe the steps ofgrinding a drill, referring as the description proceeds to the variousmechanical parts.

For each size of` drill I provide a supporting sleeve 48 and, as bestseen in Fig. 2, a supply of these sleeves 48 may be conveniently storedin a suitable rack 49 supported on the guard 50 of the grinding wheel.These sleeves have an exterior cylindrical surface adapted to fit thebearing surface 40 at the interior of the holder 38 and an interiorcoaxial surface snugly receiving the drill which may be slid into theend thereof as shown in Fig. 3. To maintain the coaxial position of thedrill relative to the holder and to provide for the clamping thereof thesleeve may be split for a portion of its length to provide (seeV Fig. 4)a major segment 5I extending over more than a semi-circumference andtherefore serving to accurately position and center the drill and aminor yieldable segment 52 which may be forced inwardly as in the mannerhereinafter described to clamp the drill in the support provided by themajor segment 5l. The sleeve and drill, as shown in Fig. 3, may then beinserted in the forward end of the holder 38 as shown in Fig. 5, theouter surface of the sleeve resting on and being centered by the bearingsurface 40. The yieldable segment 52 is provided with a slot 54 havingat its forward end the upwardly curving cam surface 56 and into thisslot 54 enters a key 58 at the interior of the holder. When the sleeveis positioned in the holder and pushed rearwardly therein by a meremotion of the fingers, the key 58 comes to the end of the flat portionof the slotl and the sleeve is positioned in a fixed positionlongitudinally of the holder while the yieldable segment 52 cf thesleeve remains unstressed and the drill can still slide within thesleeve longitudinally of the holder. In the annexed claims by majorsegment I refer to one extending over more than a semi-circumference andby minor segment to one extending over less than a semi-circumference.

To position the drill properly both longitudinally and angularly withrespect to the controlling cam elements of the holder so that it will beaccurately ground I utilize a gaging device, best shown in Figs. 1 and6. The device here shown is laterally duplicated having a portion foruse with the larger drills within the range of the machine and one forthe smaller drills, but the description of one mechanism will suflice.The gaging mechanism as a whole is organized on a suitable base hereinsupported by a post 52 (Fig. 2) from the base of the machine and has acylindrical opening 64 adapted to receive the exterior cylindricalsurface of, the drill holder in the manner seen in Fig. 6. At the rearof this opening at a position radially remote from the opening is a pin5B providing stop surfaces adapted to cooperate with one of the pins 44on the cam 42. The holder is introduced from the rear into the bearing64 and pressed forwardly until pin 65 makes contact with the face of cam42, thus determining its longitudinal position and then turned until pin44 makes contact with pin B6, thus determining the angular position.Supported in axial alignment with the bearing 64 is a gaging deviceproper 58 having an end portion formed to engage the point of the drilland the flutes at the point. Thus when the holder is inserted in thegaging device, as shown in Fig. 6, with the drill projecting, as shownin Fig. 5, it is forced rearwardly in the sleeve until it projects onlythe proper amount and as the holder is turned up to the stop 66 thedrill is held by engagement of the gage with the flutes thereof and itsangular position relative to the cam elements of the holder is thusdetermined.

'Ihe drill is now clamped in position by pressing inwardly the yieldablesegment 52 and herein the sleeve 48 is provided with threads at its rearend with which cooperate threads on a sleeve 'l0 entering the body 38from the rear and conveniently provided with a hand wheel 'l2 at therear end of the holder as a whole which will also serve as a means forturning the holder in the grinding operation. With the parts in thegaging device as shown in Fig. 6 and sleeve 10 not tightly screwed up,the holder body 38 is held by the engagement of pin 44 with stop 35.Continued rotation of the hand wheel then draws the sleeve 43 rearwardlya fixed distance causing the sloping surface 56 of the slot to ridealong the key and forcing yieldable segment 52 against the drill toclamp it in adjusted position against the positioning and centeringsurface provided by the major segment 50. This is the position of theparts shown in Fig. 6.

The holder with the drill, now clamped in adjusted longitudinal andangular position relative to the cam elements carried by the holder, maythen be removed and inserted from the rear into the holder 24, as shownin Fig. 7, and rotation of and inward pressure on the holder by means ofhand wheel 12 causes the drill in its accurately determined positiontherein to be moved by the coordinated movement of the holder in thesleeve 36 by means of the cam couple 44-46 and of the movable support 24about its pivotal axis under control of the cam couple 42-32 in suchmanner that the point and lips of the drill are properly reshaped.

I am aware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive; reference being had to the appendedclaims rather than to the foregoing description to indicate the scope ofthe invention.

I claim:

1. As a constituent mechanism of a machine of the type described, adrill holder comprising a body having an exterior cylindrical bearingsurface free of radial projections at the forward end thereof to providea bearing extending from the forward end toward the rear of the same, aradially disposed cam at the rear end of the body, a cam followerprojecting axially from the front face of the cam, a sleeve forreceiving a drill adapted to be centrally positioned in the body splitto provide a major segment to receive and center the drill and ayieldable minor segment, means in the body for cooperating with saidsegment to cause the same to grip the drill and a hand wheel at the rearof the holder operating a screw for actuating said means.

2. As a constituent mechanism of a machine of the type described, thedrill holder comprising a hollow body, a sleeve fitting therein andsplit to provide a major segment to receive and center the drill and ayieldable minor segment, a tapering key-way on the minor segment, meansin the body comprising a key entering the slot, means engaging thesleeve to move it longitudinally of the body for clamping the drill andmeans exposed at the exterior of the holder for operating the saidmeans.

3. As a constituent mechanism of a machine of the type described, thedrill holder comprising a body having an exterior cylindrical bearingsurface, a radially disposed cam at the rear end of the body, a camfollower projecting axially from the face cam, a sleeve for receiving adrill adapted to be centrally positioned in the body split to provide amajor segment to receive and center the drill and a yieldable minorsegment, a tapering key-way on the minor segment, means in the bodycomprising a key entering the slot, a screw engageable with the sleeveto move the same longitudinally and a hand Wheel at the rear of theholder for operating the screw.

GEORGE B. AMBLER.

